Chemical Substructure Index (CSI) A New Research Tool

In recent years, the extremely limited value of traditional indexes for substructure searching has become well recognized, As a result, considerable research effort has been financed for substructure search systems. However, with few exceptions, this research effort has been aimed at developing computer systems, even though most chemists do not have immediate access to computers. Manual substructure searches remain laborious or impossible to perform. The development of “desk-top” manually searchable indexes by permuting line notations was first reported in 1963,1 These indexes permit manual substructure searching that is impossible or impractical with traditional manual indexes such as the subject or formula indexes to Chemical Abstmcts, Index Chemicus, or Beilstein. Various versions of permuted line notation indexes are now used by many large organizations for internal files. However, access to the open literature for the chemist interested in finding new compounds that contain a particular substructure was unachievable prior to the introduction of the Chemical Substructure Index (CS1).